Pointed rakers

[Terry Syd]

When I refer to 'pointed rakers' I'm referring to the TOPS of the rakers. I'm not concerned about the overall shape (sharkfin, etc) nor am I concerned with the raker depth - just the point of contact of the raker with the wood.

I've been back through a number of the threads on chain sharpening and found a few hints, but I'm wondering if someone has done some experimenting on shaping the contact point of the raker.

A factory recommended angle on the TOP of the raker was 10 degrees. So, if you used a 6 degree cutting angle on the cutter, that would leave a 4 degree angle on top of the raker to glide across the wood.

Bob L. commented about using a steeper angle on the top of the raker, like 45 degrees. This would allow more 'dig in' (as he called it). It apparently helped to keep the cutter from being pulled over as much when it took a bite and thus saved wood when milling (hopefully I got that right).

Another bloke mentioned he used a 10 degree top angle from the SIDE. That is, just as he would put a 10 degree down angle on the top plate, he would use the same angle on the top of the raker. He preferred that approach when cutting softwood as he said it cut better.

OK, we all know that different raker depths work better on different wood. So how about tuning the raker point to help compensate for whatever wood you're cutting?

On some of the Aussie hardwoods I cut, even with a sharp point the raker won't dig in very much. However, if I were to cut a softwood the point could dig in deeper and I could get a bigger bite. In other words, create a chain with a raker that would change cutting angles for the type of wood I'm cutting.

It might start as a 6 degree angle in hard wood and then when the same chain was used on a softwood, the effective cutting angle would be 7 degrees.

Anybody done any experimenting with raker tops?

 

[Full Chisel]

I hit em with a file and go cut wood.

 

[Chainsaw Jim]

the only thing that matters is the depth. the angle is meant for relieving any resistance that slows the chain down.
If it is pointed then it will create drag.

 

[Deets066]

I hit em with a file and go cut wood.

X2

 

[Marshy]

IMO Your over thinkin it. It's not like anyone can hand file an angle within 6* anyways.

 

[Philbert]

If it is pointed then it will create drag.

Had the same thought. The depth gauge is designed to glide across the wood fibers, like the shoe of a plane, and control how deep the cutter edges dig in/bite/shave off. When crosscutting, a sharpened depth gauge would have to cut across the fibers, but since it is not located at the edge of the kerf, it really would not help with chip removal.

Philbert

 

[Terry Syd]

Getting the cutting angle correct isn't a problem, I use a Husky raker plate to set the angle. It was while using the plate on a Carlton chain that I noticed I could tweak it a bit and change the angle across the 'flat' of the raker. I think I can set up a raker plate to still give me a progressive cutting angle as the cutter wears, but have an increased angle on the flat the way that Bob L. mentioned. If it works, then the raker plate will do all the work.

The post that mentioned the 10 degree down angle across the top of the raker got me thinking that might be a more effective method. After setting the raker depth, just nip off a bit from the inside edge so the raker can sink further into softwood. The vertical side of the raker might also help to keep the cutter from pulling over a bit and allow a narrower kerf.

Philbert, I don't understand your comment about the kerf and chip removal. - The raker is still in the same position, it just has a different contact point with the wood.

One of the areas I cut in is a rainforest. I can go from very hard wood to soft wood in just a few paces. It would be nice to have a chain that adjusts itself for the wood.

 

[Chainsaw Jim]

It sounds like the cutting teeth are getting in the way of your rakers. you better file them teeth down so them rakers can cut wood.

 

[Terry Syd]

Had the same thought. The depth gauge is designed to glide across the wood fibers, like the shoe of a plane, and control how deep the cutter edges dig in/bite/shave off. When crosscutting, a sharpened depth gauge would have to cut across the fibers, but since it is not located at the edge of the kerf, it really would not help with chip removal.

Philbert

Come on guys, a raker doesn't promote that much drag, especially if it had a sharper edge. Think of dragging a knife across a log, not much drag in that. Hell, a cutter is chewing out a chunk of wood - that's what creates the drag. I'm sure you guys have dulled a chain and had the revs go up, but the cutting decrease. The dull cutters just slide across the wood.

If a bevel on the edge of the raker allowed it to sink a bit further into the wood, it would be the extra thickness of the chip that would create the extra drag not the thin edge of a raker.

I'll see if I can work out a sharpening technique that can do what I want. Thanks for all the encouragement.

 

[heyduke]

the only thing that matters is the depth. the angle is meant for relieving any resistance that slows the chain down.
If it is pointed then it will create drag.

the only thing that matters is the depth. the angle is meant for relieving any resistance that slows the chain down.
If it is pointed then it will create drag.

i like the simplicity of your point of view but still i have to disagree. there is a good reason for filing the correct angle on the top of the depth guage. when the cutter moves thru the wood it tilts at an angle, like an anchor on its chain for you sailers out there. if the top of the depth gauge is flat it lifts the cutter up. if the angle is correct the cutter maintains the correct depth. no, you shouldn't waste hours of time you could be cutting wood and making money, but you should be skilled enough to put a six degree angle on your depth gauge. i set my depth gauges with an oregon type grinder with a 1/4" wheel. it takes two or three minutes to do a 72dl chain.

this is why chains that are worn back to their reference mark actually cut better, because any slight error in the depth gauge height or angle has less effect due to its greater distance form the cutter.

regarding having a pointed depth gauge, it is better for it to be rounded, for the same reason, so it won't lift the cutter higher in the wood, and make a shallower cut. however, if you set the angle correctly it isn't critical.

 

[Justsaws]

The top of the depth gauge is what snaps the cutting edge back out of the wood. The amount of time the cutter is engaged depends on all sorts of variables from wood density, grain direction, chain speed, distance between cutting edges, etc... A pointy depth gauge somewhat defeats the purpose as the goal is as smooth a transition from cutter sink to cutter surface. It would probably work better to find the appropriate depth to work effectively for the types of wood to be cut and then shorten the depth gauge from inside the gullet to allow the most space for chips to accumulate in the tunnel. The rounded shape on the front of the DG is important however inside the gullet there is some unused space. Depending on the chain a pointy DG can chatter a lot, might work to your advantage on very hard types of trees but not so much on the soft ones.

The DG does sink into the wood as it is being set to snap the cutter back to surface. It controls the amount of overall drag that cutter imparts on the chain. In an ideal situation it would do this while adding zero additional drag.

If you are looking to experiment take a chain, remove the depth gauges completely. It will still work and cut wood, DGs might be completely unneeded for super hard wood in any event. Be very careful bore cutting and kick back is crazy.

One of the things that the DGs do is control vibrations from the cutting action, the other important function is provide uniformity during the process, this will become obvious after removing them. The rounded top will be smoother on the operator than a straight but angled top such as is left by the FOP unless the DG is re shaped after being lowered. This is going to be where the pointed shape does not work well.

There will probably be a substantial learning curve to a pointed DG.

I say go nuts and give it a whirl.

I would also recommend a visual side by side comparison of Oregon's VanGuard and LGX chains. Chain is sold to be used on many different saws of widely varying power, it is a compromise at best for a pitch such as 3/8 to be sold for power heads from 50cc to +100cc while spinning around bars from 14" to +60" so fiddle with it until you got what you want.

 

[heyduke]

The top of the depth gauge is what snaps the cutting edge back out of the wood. The amount of time the cutter is engaged depends on all sorts of variables from wood density, grain direction, chain speed, distance between cutting edges, etc... A pointy depth gauge somewhat defeats the purpose as the goal is as smooth a transition from cutter sink to cutter surface. It would probably works better to find the appropriate depth to work effectively for the types of wood to be cut and then shorten the depth gauge from inside the gullet to allow the most space for chips to accumulate in the tunnel. The rounded shape on the front of the DG is important however inside the gullet there is some unused space. Depending on the chain a pointy DG can chatter a lot, might work to your advantage on very hard types of trees but not so much on the soft ones.

The DG does sink into the wood as it is being set to snap the cutter back to surface.

given a properly sharpened cutter, if your depth gauges are set and shaped correctly your chips will look like corn flakes, if not they will look like corn meal.

 

[Terry Syd]

Just to clarify, there are TWO different concepts of having a pointed raker. One is the angle from the FRONT (Bob L.) and the other is the angle from the SIDE.

At this point, I'm thinking that having the SIDE angle on the top of the raker may turn out to be the best option to allow the multiple wood densities for a single chain. I don't know, I just have to experiment with it.

And there ain't no way I'm running a chain without rakers...

 

[Justsaws]

The question is what happens in the various wood, does the knife edge allow enough more travel time in softer wood for the cutter to take a larger bite before reducing chain speed to much while in much harder wood will it not sink in so much that it bogs the saw. Basically looking to accomplish the two setting on the various sharpening templates by allowing the DG to sink further in one type of wood than another, without putting to much more additional strain on the chain like a side view /\ pointed DG does, this shape will also do what you want but is scary and rough on stuff.

Also which side of the DG do you bevel for which cutter?
Bevel both sides?

DGs are a safety and convenconce option, just like the clutch.

 

[LegDeLimber]

What are the chances of the side bevel just causing the chain to get squirmy?
IF so.....
I'd expect faster wear of the bar groove and drive links and maybe some hammering of the links and top of the rails.

but I could way off here, sitting in my chair.

 

[Chainsaw Jim]

i like the simplicity of your point of view but still i have to disagree. there is a good reason for filing the correct angle on the top of the depth guage. when the cutter moves thru the wood it tilts at an angle, like an anchor on its chain for you sailers out there. if the top of the depth gauge is flat it lifts the cutter up. if the angle is correct the cutter maintains the correct depth. no, you shouldn't waste hours of time you could be cutting wood and making money, but you should be skilled enough to put a six degree angle on your depth gauge. i set my depth gauges with an oregon type grinder with a 1/4" wheel. it takes two or three minutes to do a 72dl chain.

this is why chains that are worn back to their reference mark actually cut better, because any slight error in the depth gauge height or angle has less effect due to its greater distance form the cutter.

regarding having a pointed depth gauge, it is better for it to be rounded, for the same reason, so it won't lift the cutter higher in the wood, and make a shallower cut. however, if you set the angle correctly it isn't critical.

I'm not sure why you say you disagree and then go on to describe all of what I said in a much lengthier way. Do I not mention angle and what it does? It's the second sentence.

 

[heyduke]

I'm not sure why you say you disagree and then go on to describe all of what I said in a much lengthier way. Do I not mention angle and what it does? It's the second sentence.

the only thing that matters is the depth. the angle is meant for relieving any resistance that slows the chain down.
If it is pointed then it will create drag.

i don't shape my depth gauges for "relieving resistance" or to reduce drag, but to prevent them from lifting the cutter out of the wood. there are ways of reducing drag, like filing down rivets, but who except race saw drivers has time for that? the basic problem is that two force vectors, one pulling the chain forward in a line with the rivets and another force vector pulling the chain backward, higher up at the level of the cutter, causes the cutter to tip, lifting the drive link up in front. grinding the depth gauge lower in the front helps maintain the correct depth. sorry to be so wordy. when i have time (not today) i'll draw a picture. in my experience the angle is not too critical as long as it is greater than six or seven degrees.

 

[Philbert]

Come on guys, a raker doesn't promote that much drag, especially if it had a sharper edge. Think of dragging a knife across a log, not much drag in that.

Take a sharp knife, like a steak knife. Drag the cutting edge across some wood. Then flip it over and drag the back side across some wood. You should feel a difference in drag. Now imagine that difference 700 times a second.

Philbert, I don't understand your comment about the kerf and chip removal. - The raker is still in the same position, it just has a different contact point with the wood.

I understand your side angle on the depth gauge to act as sharpening it, to almost act as a scoring cutter. Some chains (ripping, Kolve, scratcher) have separate, distinct, cutters to score through the wood fibers at each side of the kerf when crosscutting, so that the fibers can be chipped out by the 'real' rakers (the top plate on modern chainsaw cutters). Since your sharpened depth gauge would only score the fibers near the center of the kerf, it would not help as these separate scoring cutters do. They would just be making additional, shallow scoring cuts across the fibers.

One of the areas I cut in is a rainforest. I can go from very hard wood to soft wood in just a few paces. It would be nice to have a chain that adjusts itself for the wood.

Agreed, that would be nice!

With storm damaged wood or firewood, I never know what I am going to cut next, so I sharpen for general purpose cutting - not optimized for anything. If you know what you are going to cut, you can have different chain loops optimized for each species/situation.

Philbert

 

[heyduke]

Take a sharp knife, like a steak knife. Drag the cutting edge across some wood. Then flip it over and drag the back side across some wood. You should feel a difference in drag. Now imagine that difference 700 times a second.


I understand your side angle on the depth gauge to act as sharpening it, to almost act as a scoring cutter. Some chains (ripping, Kolve, scratcher) have separate, distinct, cutters to score through the wood fibers at each side of the kerf when crosscutting, so that the fibers can be chipped out by the 'real' rakers (the top plate on modern chainsaw cutters). Since your sharpened depth gauge would only score the fibers near the center of the kerf, it would not help as these separate scoring cutters do. They would just be making additional, shallow scoring cuts across the fibers.


Agreed, that would be nice!

With storm damaged wood or firewood, I never know what I am going to cut next, so I sharpen for general purpose cutting - not optimized for anything. If you know what you are going to cut, you can have different chain loops optimized for each species/situation.

Philbert

where i live and work we have everything from pillow-soft pondeosa pine to iron-hard honey locust. i use the same repeatable, precise sharpening for all types of wood. i adapt by varying my cutting technique.

 

[Chainsaw Jim]

The cutting tooth creates a pinch on the noodle up against the raker because of the angle of the tooth forcing it to dig deeper. And as we all know, the raker stops it from digging deeper, but there is considerable pressure on the raker so it needs to have a smooth surface with an angle to prevent the raker from biting in.

Yes, I'm bored. I think it's time to go build a couple 372xpw's.